HARRISBURG, Pa. -- An effective blood substitute has long been a "holy grail" for trauma care.

But a national study that included Penn State Milton S. Hershey Medical Center indicated that accident victims given a blood substitute had no better chance of surviving than people given saline, the normal treatment when blood isn't immediately available.

The study focused on PolyHeme, which is made from blood but can be stored longer and given to people of any blood type. Ambulances don't carry real blood, mainly because of storage issues and because people need their own blood type.

PolyHeme has the benefit of being able to carry oxygen to the brain and organs. Saline can maintain blood pressure but can't carry oxygen.

If the victims fared better, it would be a huge accomplishment that could improve survival and recovery rates for people who can't get real blood quickly, such as those injured in a remote area or who were trapped in a vehicle, said Dr. Robert Cherry, who led the study at Hershey.

"I think we're still in the early stages of where this is going to evolve," he said.

A company that gains government approval for a blood substitute could reap significant profits.

The study involved 32 U.S. trauma centers and 714 people who were in shock due to blood loss.

Nationally, 349 people received PolyHeme and 365 received saline. Of those who received PolyHeme, 46 died. Of those who received saline, 36 died.

At Hershey, nine people were in the study. Five got saline and four got PolyHeme. Two died -- one who received PolyHeme and one who received saline.

Cherry said the differences in mortality rates aren't statistically significant.

He said the study focused on mortality rates of people who received PolyHeme. It didn't look at whether people who received PolyHeme, with its ability to carry oxygen, had better outcomes.

The study was unusual in that it involved people who were unable to give the consent that's normally required of people involved in medical experiments.

The government gave an exception available for studies of potentially life-saving treatments in situations were it's not practical to obtain consent.

The medical center had to describe the study at meetings around the region and obtain feedback before deciding to participate.

People could opt out, and 125 local residents obtained wrist bands that would tell emergency workers they didn't want to be in the study.

Controversy erupted during the study when the Journal of the American Medical Association published a study suggesting health risks related to various experimental blood substitutes had been hidden.

The authors reviewed studies of five blood substitutes, and said the results showed people who received them had a 30 percent higher death rate, and were three times more likely to have a heart attack.

In the PolyHeme study, 11 patients who received the substitute had heart attacks, compared with three who received saline. None of the Hershey patients had a heart attack.

Cherry said he wouldn't dismiss the concerns raised in the study. But he said he believes Hershey officials were given sufficient information and were able to adequately inform local residents.

"Our experience here at Hershey is that we have a very positive experience with the product," he said.

A spokeswoman for Northfield Laboratories, the Illinois company that makes PolyHeme, didn't return a message Tuesday afternoon.

INFOBOX:THE POLYHEME STUDY* Nationally, 714 trauma patients were in enrolled in the study. That included nine at Penn State Milton S. Hershey Medical Center.* Nationally, 349 people received PolyHeme, and 365 got saline. At Hershey, five got saline, and four got PolyHeme.* Nationally, 46 patients who received PolyHeme died, as did 36 people who received saline.* At Hershey, one person who received PolyHeme died, and one person who received saline died.* Nationally, 11 patients who received PolyHeme had heart attacks and three patients who received saline had heart attacks. None of the Hershey patients had a heart attack, officials said.